Chromatography is the separation of a mixture of compounds (solutes) into separate components. This separation permits the composition of all or part of the mixture to be determined. In gas chromatography, a gas chromatograph (commonly called a “GC”) is utilized to separate and determine the quantities of components of a gas mixture. A gas chromatograph performs these functions by taking a sample of the gas mixture to be analyzed and injecting it into a carrier gas stream, such as helium or hydrogen, which then carries the gas sample through one or more tubes (referred to as columns) that are packed with a very fine particulate material. Each of the particles of this material are coated with a film from liquid that controls the rate at which the different components of the gas sample are absorbed and de-absorbed by the particulate material. This rate of absorption and de-absorption also varies relative to each of the different components. Because of this differing rate of absorption and de-absorption, certain gas molecules related to one type or component of gas will exit the column more quickly than some of the other components will. This process of separation of components permits a detector located at the end of the column to quantify the amount of a particular component that is present in the mixture.
Gas chromatographs having a modular construction are known in the prior art. Examples of modular gas chromatographs are disclosed in U.S. Pat. No. 4,044,593 to Haruki et al.; U.S. Pat. No. 5,105,652 to Manfredi et al.; U.S. Pat. No. 5,340,543 to Annino et al.; and U.S. Pat. No. 5,808,179 to Sittler et al. The modular gas chromatographs disclosed in the foregoing references each have a module known as an analysis or GC module, which includes one or more columns for separating gas components. Some of these GC modules include detectors and more particularly, thermal conductivity detectors. None of these GC modules, however, include other electronic devices that can provide information to a control unit controlling the gas chromatograph in which the GC module is mounted.
Based on the foregoing, there is a need in the art for a GC module containing an electronic device other than a thermal conductivity detector. The present invention is directed to such a GC module.